Simple PHP script to decrypt WHMCS hashed strings

WHMCSDecryptor.php

<?php
$encoded_string = "JATa2iUqVdzCkBP5RiyitlQlUiACl8UrpJOeGUJO";
$cc_encryption_hash = "SOmECRAZYLONGHASHROFLCOPTERBBQKTHX";

echo decrypt_whmcs($encoded_string, $cc_encryption_hash);

function decrypt_whmcs($encoded_string, $cc_encryption_hash) {
    $key = md5(md5($cc_encryption_hash)) . md5($cc_encryption_hash);
    $hash_key = _hash($key);
    $hash_length = strlen($hash_key);
    $string = base64_decode($encoded_string);
    $tmp_iv = substr($string, 0, $hash_length);
    $string = substr($string, $hash_length);
    $iv = $out = "";
    for($c = 0; $c < $hash_length; $c++) {
        $iv .= chr(ord($tmp_iv[$c]) ^ ord($hash_key[$c]));
    }
    $key = $iv;

    for($c = 0; $c < strlen($string); $c++) {
        if ($c != 0 && $c % $hash_length == 0) {
            $key = _hash($key . substr($out, $c - $hash_length, $hash_length));
        }
        $out .= chr(ord($key[$c % $hash_length]) ^ ord($string[$c]));
    }
    return $out;
}

function _hash($string) {
    if (function_exists("sha1")) {
        $hash = sha1($string);
    } else {
        $hash = md5($string);
    }

    $out = "";

    for($c = 0; $c < strlen($hash); $c += 2) {
        $out .= chr(hexdec($hash[$c] . $hash[$c + 1]));
    }
    return $out;
}